(Reuters) -The movement of a flight deck seat is a key focus of the probe into a sudden mid-air dive by a LATAM Airlines Boeing 787 plane that left more than 50 people injured, aviation industry publication the Air Current reported on Wednesday.

The plane, which was heading from Sydney to Auckland on Monday, dropped abruptly before stabilizing, causing those on board to be thrown about the cabin.

Based on the available information it was understood the seat movement was "pilot induced, not intentionally," the report said, citing a senior airline safety official.

"The seat movement caused the nose down" angle of the aircraft, the publication said, citing another anonymous source who added the possibility of an electrical short was also under review.

Boeing is expected to release a message to 787 operators regarding the incident, the Air Current reported, in a sign a fleet-wide issue could be involved though it said the specific topic was not known to the publication.

Boeing declined to comment on the report, instead referring Reuters to the investigating agencies.

Chile's aviation regulator, which is leading the probe given it involves a Chilean airline flying in international airspace, said the investigation "just got underway" and its investigators had arrived in New Zealand.

LATAM said it "continues to work in coordination with the authorities to support the investigation" and said it was not appropriate to comment on speculation that has circulated.

LATAM is based in Chile and the flight, which had 263 passengers and nine crew members, was due to continue on to Santiago after stopping in Auckland.

The cause of the flight's apparent sudden change in trajectory has not yet been explained. Safety experts say most airplane accidents are caused by a cocktail of factors that need to be thoroughly investigated.

New Zealand's Transport Accident Investigation Commission said on Tuesday it was seizing the cockpit voice recorder and flight data recorder of the flight, which would provide information about the conversations between the pilots and the plane's movement.